When we teach the push press we focus on driving through the heels so that our athletes will use their hip and butt and stay balanced. Inevitably when an athlete extends the legs hard enough they may come up onto the toes. As long as this is a follow through of vicious leg extension it is not a big worry. A much bigger problem is going on the toes in the dip phase which is likely to lead to being off balance, inefficient and less powerful.